The 5000-series CTA cars, the city's first new edition in almost 20 years, returned to the rails this weekend after a lengthy sabbatical to fix some defective parts. That sent me off on a search for a brief visual history of CTA cars, from their steam-pulled past—remarkably, some of the steam-drawn cars, built at the turn of the century, survived into the 1950s as unpowered coaches—to the latest edition.

Normally I'm too distracted by Angry Birds or a book to pay much attention to what sort of car I'm on, but as samey as they can seem, running around us is a visual history. It's not quite the hodgepodge it was during the mid-20th century; during the 1960s, four different series of all different colors and makes were in use, from the ancient Plushies to the cheery 6000 series to the mod 2000 series. In the 1970s, the CTA enlisted the great architectural firm of Skidmore, Owings, and Merrill for a complete design overhaul, and we got the 2200: a sleek, boxy, minimalist car that remains in use today, though it's being supplanted by the 5000 series, and has basically defined the look of the el ever since (though the 70s Bicentennial 2400 and the 80s 2600 were very much of their era). After trying to dress them up a bit in the city colors, the familiar 3200 and the new 5000 are updates on the look SOM defined.

The CTA's Flickr site has a nice trove of vintage photos to go along with obsessively detailed photographic accounts of station improvements; all the photos are from there unless otherwise noted. Here's a quick tour through the years of design, with some detours.